Error: Failed to initialize database (in AIR Help output from RH10)

Hi, I recently upgraded a RH8 project to RH10. The project is a multiple merged help system as described in

http://blogs.adobe.com/techcomm/2010/07/merging_multiple_helps_in_air_ help_output.html

The merged AIR Help output from RH8 worked fine, but now when you search for any text in AIR Help from RH10, the message "Error: Failed to initialize database" appears.

All other aspects of the upgraded AIR Help project seem to be ok. Is this a known issue with RH10 Air Help?

Thanks in advance!